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 The number of home PCs is increasing rapidly  Most of the PCs are “fat clients”  As the Internet usage grow, more and more PCs are connecting to the global net  Most of the time PCs are idle  How can we use all this? 7/66 Peer-to-Peer (P2P)

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 “Peer-to-peer is a way of structuring distributed applications such that the individual nodes have symmetric roles. Rather than being divided into clients and servers each with quite distinct roles, in P2P applications a node may act as both a client and a server.” 8/66

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 Distributed Hash Table  Input: key (file name) Output: value (file location)  Each node is responsible for a range of the hash table, according to the node’s hash key. Objects’ directories are placed in (managed by) the node with the closest key  It must be adaptive to dynamic node joining and leaving 12/51